This invention relates to an improved-push-to connect tubing fitting for engaging nylon tubing or tubing of like material. More specifically, the improved push to connect tubing fitting seals the tubing connection prior to mechanical engagement of the tubing to the fitting Upon insertion in the fitting, the tubing engages a sealing means prior to engaging the tubing gripping devices of the collett.
The purpose of the prior art push-to-connect tubing fittings is to allow assembly and disassembly of tubing connections without tools and as rapidly as possible. The tubing has a soft exterior and is circular in cross section. An example of a prior art tubing fitting with tubing assembled within the fitting is shown in FIG. 5. The prior art fittings 10 had a body 11 with a bore 12 in it. A collett 13 was positioned within the bore 12 of the body 11 to mechanically engage the nylon tubing 20 upon its insertion. The collett 13 had a bore 15 extending along the same axis as the bore 12 of the body 11 and all the way through the collett 13. Tubing gripping devices 16 were present on the inner surface of the bore 15 in the collett 13, at the end of the bore opposite the tubing insertion opening. The diametrical distance between radially opposite tubing gripping devices 16 was slightly less than the diameter of the outer surface of the tubing 20. Thus when the tubing 20 was inserted into the fitting 10, the end of the collett 13 opposite the tubing insertion opening was elastically deformed radially outward and the tubing gripping devices 16 engaged the outer diameter of the nylon tubing 20.
The prior art tubing fitting 10 had further structure to more positively engage the tubing 20 to the fitting 10. Radially outward of the tubing gripping devices 16 the collet 13 had ramped surfaces 24 on its outer surface which sloped toward the axis of the bore 15 in the collett 13 in the direction from the end farther from the insertion opening to the end closest to the insertion opening. The body 11 of the fitting 10 defined ramped surfaces 25 adjacent its inner bore 12 which also sloped toward the axis of the bore 12 from their end furthest from the tubing insertion opening to their end closest to the tubing insertion opening. The collett 13 was positioned in the body 11 of the fitting 10 such that the ramped surfaces 24 on its outer surface were disposed adjacent to but radially inside and further from the tubing insertion opening than the ramped surfaces 25 defined by the inner surface of the body 11 of the fitting 10. Thus, after the nylon tubing 20 was inserted into the fitting 10 the gripping devices 16 of the collett 13 would engage the nylon tubing 20. If thereafter, a force was applied to the tubing 20 in the proper direction to remove the tubing 20 from the fitting 10, the tubing 20 and the collett 13 would be forced as a unit toward the tubing insertion end of the fitting 10. This brought the ramped surfaces 24 on the outer surface of the collett 13 into facial engagement with the ramped surfaces 25 on the inner surface of the body 11 of the fitting 10 and caused the end of the collett 13 opposite the tubing insertion opening to constrict radially inward. Under such circumstances the inward force of the tubing gripping devices 16 on the tubing 20 was increased and the strength of the mechanical engagement between the tubing 20 and the collett 13 was further increased. In many instances a rigid cylindrical sleeve 27 was fixedly attached to the body 11 of the fitting 10 concentrically within the bore 12 of the body 11. This sleeve 27 protruded into the bore 12 of the body 11 toward the outer end of the fitting 10. The outer diameter of the sleeve 27 was slightly smaller than the inner diameter of the nylon tubing 20. When the tubing 20 was inserted into the fitting 10, the end of the tubing 20 slid over and surrounded the free end of the sleeve 27. The sleeve 27 thus supported the inside of the tubing 20 and prevented the tubing 20 from collapsing inward as increased force was applied to the outside of the tubing 20 by the tubing gripping devices 16 of the collett 13.
The sealing device 44 of the prior art tubing fitting 10 was disposed farther from the tubing insertion opening than were the tubing gripping devices 16 of the collett 13. The prior art fitting 10 had the sealing device 44 positioned co-axially inside the bore 12 of the body 11 at a point farther from the tubing insertion opening than the tubing gripping devices 16 of the collett 13. Thus as the tubing 20 was inserted into the fitting 10, it would first engage the tubing gripping devices 16 of the collett 13, and then as it was inserted farther into the fitting 10 it would sandwich the sealing device 44 between the outer surface of the tubing 20 and the bore 12 of the body 11. This effectively sealed the tubing 20 to the fitting 44. The tubing gripping devices 16 of the collett 13 often marred the outer surface of the tubing 20 which was to seal against the sealing device 44. In addition, the tubing 20 was often inserted into the fitting 10 far enough to engage the tubing gripping devices 16 of the collett 13 but not far enough to engage the sealing device and the connection would leak.
As a result,xe2x80x94an object of the present invention is to provide a fitting which allows quick, easy assembly and disassembly of a tubing connection without the use of tools and to further ensure that the tubing cannot be mechanically engaged by the fitting without being sealed to the fitting. A second object of the invention is to provide a fitting which does not mar the portion of the outer surface of the tubing which engages the sealing device.
The fitting of the present invention is similar to the fittings of the prior art. The fitting of the present invention has a body with a bore in it. A collett is positioned within the bore of the body and has a bore through it approximately parallel to the bore of the body. The collett has tubing gripping devices on the inner surface of its bore. A sealing device is positioned co-axially inside the inner bore of the collett at a point closer to the tubing insertion opening than are the tubing gripping devices of the collett. Another sealing device is positioned between the outer surface of the collett and the inner surface of the bore in the fitting body. Thus, when the tubing is inserted into the fitting, it first engages the sealing device on the inside of the collett and after it is further inserted into the fitting mechanically engages the tubing gripping devices of the collett. This causes the tubing to be sealed to the collett before it is mechanically engaged to the fitting. The sealing device positioned between the collett and the body of the fitting seals the collett to the body of the fitting and thus completes the sealing of the tubing to the fitting The use of a sealing device between the collet and the body is an alternative to different structures which effectively complete the sealing of the tubing to the fitting but make it necessary to use tools to disassemble the tubing from the fitting.
It can thus be seen that above described device accomplishes both of the objects of the invention. The first object is accomplished because the tubing must be inserted into the fitting far enough to engage the sealing device inside the bore of the collett before it engages the tubing gripping devices of the collett. Thus it is not possible to insert the tubing into the fitting tar enough to mechanically engage the fitting without the tubing having first engaged the sealing device inside the collett. The second object is accomplished because the portion of the outer surface of the tubing which engages the sealing device inside the collett has not contacted the tubing gripping devices of the collett and thus has not been marred.